1. Field of the Invention
This invention relates to apparatus for cleaning floors, walls, carpets, curtains, upholstery and the like. The invention is more particularly concerned with a dual purpose apparatus suitable for both dry suction cleaning and water extraction cleaning processes.
In the process of water extraction cleaning, a carpet or the like is thoroughly wetted by a solution containing a suitable cleansing agent, such as a nonfoaming detergent, and the carpet or the like is then substantially dried by uptake of the solution by suitable suction apparatus.
2. Description of the Prior Art
Various types of dual purpose appliances have been proposed in previous publications, but none appears to have met with any degree of commercial success. For example, British Patent Specification No. 1,121,225 discloses an attachment for use with an external source of suction, such as a conventional dry suction cleaner (vacuum cleaner) wherein a clean water reservoir is provided within a soiled water collection container, and liquid from the reservoir is delivered by virtue of the reduced pressure in a cleaning head to which suction from the external source is applied by way of the collection container. Whilst such an attachment can be used with a conventional vacuum cleaner to provide the additional function of a wet cleaning process, it has a number of disadvantages. In particular, the provision of the clean water reservoir within the collection container greatly restricts the volume of liquid that can be collected; delivery of the clean liquid by suction established in the cleaning head results in the liquid being drawn away before it effectively penetrates the carpet being cleaned; and as the attachment may be used with any conventional vacuum cleaner, it is impossible to be certain that the suction power available will be sufficient to operate the attachment efficiently. Additionally, such an attachment is relatively expensive to produce since it utilises only the suction means of the conventional cleaner with which it is used and not the collecting capacity thereof.
Another approach is shown in U.S. Pat. No. 3,079,626. This shows a dual purpose cleaner which is effectively two separate appliances which share a single suction unit that is designed to be assembled with either of the appliances. This arrangement is again unduly costly for ordinary domestic use where the vacuum cleaning appliance is likely to be in daily use and the wet process cleaning appliance may only be used for a few days in the year.
A rather different approach is shown in German Pat. No. 2,539,832. This shows an appliance which incorporates a dust filter and a clean water reservoir at the same time, so that either function may be employed at any time. However, in this case the reservoir reduces the collecting capacity of the container even when the appliance is in use as a dry vacuum cleaner, and moreover a separate pump is provided to dispense the cleaning liquid when required. Whilst the additional expense involved in providing such a separate pump may be acceptable for a commercial or industrial cleaning appliance, it is not acceptable in an appliance intended mainly for domestic use.
With a view to overcoming these disadvantages and providing a dual purpose appliance which is suitable for domestic use, the Applicants have already proposed in their U.S. patent application No. 905,417 a dual purpose appliance in which a clean water reservoir and a filter unit are interchangeably assembled with a suction unit and a collection container in such a manner that the exhaust air from the suction unit is utilised to deliver liquid from the reservoir when the latter is in use, and the full volume of the container is available for collecting dry matter when the filter is in use. The present invention provides an improved arrangement whereby means for control of the exhaust air flow is built into the interchangeable parts of the appliance and obviates the need for movable parts to direct such air flow along different paths according to the function for which the appliance is set up.